Manufacture of oil soluble phenols



S acetate i ll, J-uuv ratentea 0v.

g 2,060,965 MANUFACTURE OF OIL SOLUBLE PEENOLS Charles P. Wilson, Jn,Houston, Tex.

No Drawing. Application August 15, 1934, Serial No. 739,935

9 Claims. (Cl. 260-154) V This invention relates to a method ofpreventing deterioration of oils, fats, and rubber, and is applicable tosubstances liable to oxidation. The a process and product will bedescribed more particularly in relation to inhibiting auto-oxidation ofmotor fuels resulting from pyrolysis of heavy oils or coal.

Color deterioration and gum formation are known to be the result ofoxidation. Color deterioration does notrender motor fuel or motor oilunfit for ,use, but lowers its market value. Gum formation is the resultof oxidation of unsaturated hydrocarbons, and when present in motor fuelinsmall quantities renders the fuel unfit for use in an internalcombustion engine. To obtain gum-free and stable products, the usualpractice is to remove a substantial quantity of the unsaturatedhydrocarbons through treatment with sulfuric acid, or through thecontrol of the cracking plant in such a manner as not to produce a highconcentration of the unstable unsaturated hydrocarbons. Control of thecracking process in this way sometimes results in a lower percentage ofcracked fuel, and the sulfuric acid treatment always results in a loss,which in many cases runs as high at 5% of the motor fuel produced. Thistreatment is costly and wasteful, and also results in a lowering of theantiknock value of the motor fuel.

The primary object of the invention is the manufacture and use of anoxidation inhibitor which, when added in minute quantities, preventsdeterioration of hydrocarbons and various oils liable to oxidation. Itis particularly useful in the manufacture and marketing of motor fuelcontaining unsaturated hydrocarbons liable to oxidation, since it notonly inhibits gum formation in storage, but actually reduces the gumyield when the cracked product to which the inhibitor has been added istested for gum by the copper dish method. In the majority of cases onlya minute quantity of the inhibitor, the cost of Corina Drsn Tasrs Sample1 amounstdolgnhibitor Q l oo v (gms. per cc.) per Nil 0.103 0.002 0.0480.005 0, 008 0. 018 0.025

Sample 2 Nil 0. 183 0.0007 0.101 0.0014 0.056 0.0035 0.008 0. 007 0. 011

I have found that the following substances are effective in preventinggum formation when added in minute quantities to oils:

pyrogallol para-aminophenol. catechol para-phenylenediamine hydroquinonemethylaminophenol ortho-aminophenol alpha-naphthol Numerous othercompounds, such as cresol, dimethylaniline, etc, have a slightstabilizing effect, but my experience has been that as a general ruleonly aromatic compounds with two bydroxyl and/or amino groups in theortho or para positions of the benzene ring will completely preventoxidation, although it willbe noted that alpha-naphthol, which has onlyone hydroxyl group, is an exception. The presence of other groups in thebenzene ring in addition to the above mentioned does not destroy theinhibiting action.

All of the above mentioned substances except alpha-naphthol are moresoluble in water than in oil, in which they are nearly insoluble, andthey are not satisfactory for use in practice for the commercialstabilization of motor fuels on account of thefact that it is difficultto prevent the latter from coming into contact with water.

Naphthol cannot be used, since it causes motor fuel to deteriorate incolor, although it is satisfactory as regards solubility.

I have found that if an alkyl or aryl group is substituted for ahydrogen atom in these compounds, their solubility in water isdecreasedand their solubility in oil is increased without an appreciable loss intheir power to inhibit oxidation. The greater the number of alkyl oraryl groups which can be substituted in the benzene ring, the moresoluble is the resulting compound in the hydrocarbon to be stabilizedand the less soluble in water.

The new and novel features of the present invention are. the productionof oil-soluble oxidation inhibitors from certain types of oil-insolublephenolic or amino compounds, by substitution of one or more alkyl oraryl groups for hydrogen atoms; an improved method of introducing analkyl group into a phenol; and the utilization of turpentine, a liquidsulfur dioxide extract of an oil, or the unsaturated hydrocarbonsderived from the pyrolysis of oil or coal, as the base or stock fromwhich the substituted phenolic or amino compound is produced; oilscontaining mixed unsaturated hydrocarbons are very much cheaper than thepure unsaturated compounds, but are equally satisfactory for thepreparation of the substituted compound.

The introduction of alkyl groups is eflected by a modification of themethod of Koenigs (Ber. 23,

3144; 24, 1'79, 3889; 25, 2649) who prepared alkylsubstituted phenols byallowing a mixture of one part of the phenol with the equivalent amountof an unsaturated hydrocarbon to stand for several days in the presenceof one part of concentrated sulfuric acid and nine parts of acetic acid.My improvements that are new to the art are as follows:

l. The use of a mixture of unsaturated hydrocarbons, such as turpentine,a liquid sulfur dioxide extract of an oil, or an oil derived from thepyrolysis of oil or coal. Such oils should preferably contain a largepercentage of unsaturated hydrocarbons, as high concentrations of thelatter cause the reaction to take place more readily.

2. The use of dilute sulfuric acid (about 50%) instead of concentratedacid. This prevents loss of the phenolic compound by eliminating sidereactions such as the formation of acetates.

3. The use of a much smaller quantity of sulfuric and acetic acid, thusreducing the cost of manufacture.

4. Carrying out the reaction at an elevated temperature with agitation.This reduces the time required to a few hours.

.5. The use of a considerable excess of unsaturated compounds, in orderto avoid loss of the more costly phenol.

6. Incomplete removal of acetic acid from the solution of alkylsubstituted phenol. A trace of acid present in the solution acts as apreservative, preventing oxidation of the compound itself before it isadded to the oil to be stabilized.

7. The use of a dilute solution of a mineral acid for extracting theacetic acid instead of water or ammonium carbonate. Oxidation of thecompound during the washing is thus prevented.

It will be noted that by alkylation of the various oil-insolubleoxidation inhibitors, such as pyr0-,

gallol and aminophenol, in various ways, an almost infinite number ofdifferent compounds can be obtained which would be suitable forinhibiting the oxidation of oils. For the preparation of the varioustypes of compounds, a number of difierent methods are available. Forexample, amyl pyrogallol may be prepared by the action of amyl alcoholon pyrogallol in the presence of anhydrous zinc chloride; andaminophenol can be alkylated by heating under pressure with alcohols;-or the reaction between pyrogallol and unsaturated hydrocarbons willtake place tosome extent without a catalyst, or with aluminum chloride.I have, however, found that the cheapest and easiest compounds tomanufacture are those prepared from pyrogallol by the method describedabove. Catechol also gives good results by this method, but is moreexpensive. Examples of the preferred method of preparation using crackeddistillate and turpentine are given below:

Five parts by weight of powdered pyrogallol, ten parts of glacialacetic' acid, one part of 50% sulfuric acid, and ten parts of crackeddistillate are placed in an acid-resisting container fitted with astirrer and a reflux condenser, and supplied with facilities forheating.The mixture is agitated violently, and heated to boiling. The agitationand heating are continued for two hours, '75 parts of cracked distillatebeing gradually added during this period. After two hours, whensubstantially all of the pyrogallol should have entered into combinationwith the unsaturated hydrocarbons present, the agitation is stopped andthe product allowed to cool in an oxygen-free atmosphere. The reactionwhich occurs is probably as follows:

R.CH:CH: plus 0611x011), gives BCHz-CHi-C6H$(OH)1 olefine pyrogallolstabilizer The resulting mixture consists of a solution of the oxidationinhibitor and acetic acid in the oil which supplied the unsaturatedhydrocarbons,

and a layer of sludge on the bottom of the containing vessel. Twentyparts of 0.1% sulfuric acid are introduced, and the mixture is agitatedfor fifteen minutes for the purpose of removing excess acetic acid. Thewashing also causes any substituted compound contained in the sludge toreturn to the oil solution. The lower layer is drained oh, and theextraction repeated twice. The solution of oxidation inhibitor thusprepared is then run into a storage vessel, preferably of copper orwood.

When turpentine is used, forty parts of pyrogallol are dissolved byheating and agitation in sixty parts of glacial acetic acid. One part of50% sulfuric acid is added, and ahunclred parts fresh turpentineintroduced while the mixture is being agitated. Heat is evolved, andcare must be taken that the temperature does not rise above 100 C. Whenall the turpentine has been added,

' the mixture is maintained at about 90 C. until the reaction is.substantially complete. After cooling, it may be diluted by a suitableoil. It is then washed as in the previous example. The amount of thesubstituted compound formed is substantially twice the weight ofpyrogallol used. I have found that acetic acid acts as a preservative ofthe compound, but most of it must be removed as it would cause the motorfuel to which the above described inhibitor had been added to becomecorrosive. The acetic acid may be removed by extraction with anysuitable solvent, such as water or a mineral acid, or by other suitablemethods such as distillation, instead of by dilute sulfuric acid asdescribed in the above examples v Referring more particularly to the useof a sulfur dioxide extract of an oil, mentioned heretofore, I havefound it advantageous to use an extract of cracked distillates, such ascracked gasoline, naphtha or kerosene. The distillate may be from anasphaltic, mixed or paraffin base crude. I have obtained good resultswith a cracked distillate obtained by cracking a gas oil from a mixedbase crude. The cracking may be done in the liquid or vapor phase, butthe invention may find best application in treating a distillate.

distillate that is not extensively cracked, such as that from a liquidor semi-liquid phase cracking operation wherein the unsaturated contentmay vary from 10-30%, since the highly cracked vapor phase distillatescontaining 40-60% unsaturation may be used as such without furtherconcentration of the unsaturated constituents. While I have mentionedspecifically the extraction with liquid sulfur dioxide, I may use otherselective refining solvents, such as furfural, nitrobenzene, phenol ormixtures thereof with modifying solvents, which function in asubstantially equivalent manner to sulfur dioxide, i. e. which effect aseparation of constituents useful in my invention from the distillateextracted.

In the extraction of the cracked distillate the The extraction isusually carried out at a low temperature, say around zero, in the caseof liquid sulfur dioxide or at a somewhat higher temperature with acorrespondingly higher pressure in order to maintain the solvent in theliquid phase. The ratio of solvent to oil may be adjusted to effect therequired separation and this will readily be done by the skilledoperator. The extraction should be conducted so that a large proportionof the unsaturated constituents of the oil is extracted by the solvent.Aromatic hydrocarbons and a substantial amount of sulfur compounds, ifpresent, will also be extracted but these are usually not objectionable.In case the amount of sulfur compounds is large, it may be reduced bytreating with sulfuric acid or other suitable desulfurizing operation.

The extract is readily recovered from the sol- -vent by vaporization ofthe solvent; for example,

in the case of sulfur dioxide the solvent readily volatilizes on releaseof the pressure. The quantity of extract will vary with the oil treatedbut usually runs from about 15-30% of the distillate. It is highlyunsaturated and normally of slightly higher gravity and boiling-pointthan the original I The unsaturation of the-extract will be high andwill vary according to the selectivity of the solvent. It is notnecessary to obtain a product consisting entirely of unsaturatedcompounds since such a material might even be too reactive; accordingly,it is often advantageous to have present a substantial amount ofaromatics, naphthenes or parafins as diluents.

As an example of the operation of this modification of the invention thefollowing may be cited:

A mixed base cracked distillate from a com- 65 mercial crackingoperation, such as the Holmes- Manley, was treated with liquid sulfurdioxide and the oil separated into an upper layer, comto remove theremainder of the sulfur dioxideand some of the othersulfur compounds.Five parts of pyrogallol, ten parts of glacial acetic acid, one part of50% sulfuric acid were mixed with ten parts of the extract and themixture refluxed for about two hours during which time 40 parts more ofthe extract were gradually added.

The mixture was then cooled and the excess acids washed out with 0.1%sulfuric acid. The product was then ready for useas a gum inhibitor.

It has been found that the substituted compound when prepared asdescribed above may .be

stored for a long period of time, at least as long as two years as shownby practical tests, without losing activity as a stabilizer.

I have found that a compound as thus prepared is acidic and that it canbe removed or destroyed by shaking with alkalies, such as sodiumcarbonate or caustic soda. It is, therefore, necessary to prevent themotor fuel from coming into contact with alkaline substances after theaddition of the inhibitor. The compound is also destroyed by organicperoxides, and to prevent this it is advantageous that the motor fuel befresh and free from peroxides when the compound is added.

The gum content of Samples 3 and 4 shown hereunder has been determinedby the U. S. Bureau of Mines Steam OvenMethod, in which a 20 cc. sampleof motor fuel is evaporated in a steam oven from which oxygen isexcluded. The gummy residue obtained in this manner is considered torepresent the actual or inherent gum present in the fuel.

The gum content of Samples 1 and 2 hereinbefore described under copperdish tests was determined by evaporating cc. of cracked gasoline on asteam bath. In this test the gasoline is exposed to atmospheric oxygenduring the evaporation and although a sample of cracked gasoline gives aconsiderable residue by thismethod, the same sample might be found to beentirely free from inherent gum as determined by the steam oven' method.

Results of storage tests made on identical cracked gasolines, with andwithout addition of inhibitor, are given below. The samples consist ofcracked gasoline stored in the dark in glass bottles vented toatmosphere:

Sample N 0. 4

Steam oven gum (gins. Color (Saybolt chromomper 20 cc.) eter) Time ofstorage (weeks) Without Q Without with 0-0005 pe een ercent m inhibitori hibitor Nil Nil Plus 25 Plus 25 Trace N11 Plus 25 Plus 25 Trace TracePlus 25 Plus 25 The term selective refining solvent, as used in theclaims, refers to commercial solvent. refining agents which, as commonlyunderstood in the petroleum industry, extract soluble in the solvent theunsaturated naphthenic and aromatic hydrocarbons from the tuted phenolscontaining said unsaturated coninsoluble parafiinic hydrocarbons.

The term fsolvent refining extract, as used in the claims, refers tothat portion of the oil which is soluble in and extracted by the abovedescribed selective refining solvent.

From the above description it will be evident that while I havedescribed and claimed the preferred embodiment of the invention, it isto be understood that I reserve the right to make all changes properlyfalling within the spirit of the invention and without the ambit of theprior art.

This application is a continuation in part of my application Serial No.730,728, filed June 15, 1934, which'in turn is a continuation of SerialNo. 503,095, filed December 1'7, 1930.

I claim:

1. A process for the preparation of oil-soluble phenols, which comprisescondensing a phenol with a sulfur dioxide extract of a hydrocarbon oilin the presence or ea ariddilute sulfuric acid, whereby substitutedderivatives of said phenol containing components of said extract assubstituted groups, are formed.

2. A process for the preparation of oil-soluble phenols, which comprisescondensing a polyhydric phenol with a sulfur dioxide extract of acracked hydrocarbon oil in the presence of heat and dilute sulfuricacid, whereby substituted phenols containing components of said extractas substituted groups, are formed;

selectively separate as anthe ortho and para positions with unsaturatedconstituents extracted from a cracked hydrocarbon distillate by'sulfurdioxide, whereby substistituents and substituted groups, are formed.

4. A-process for the preparation of oilsoluble phenols, which comprisesreacting a polyhydric phenol with a sulfur dioxide extract of a crackedhydrocarbon distillate while in the presence of acetic and a smallamount of sulfuric acid to form substituted phenol derivativescontaining components of said extract as substituted groups.

5. A mixture of oil-soluble phenols, consisting essentially of acondensation product of a phenol and a sulfur dioxide extract of ahydrocarbon oil, said phenols containing components of said extract assubstituted groups.

6. A mixture of oil-soluble phenols, consistimg essentially of acondensation product of a poly hydric phenol and a sulfur dioxideextract of a cracked hydrocarbon oil, said phenols containing componentsof said extract as substituted groups.

7. A mixture of oil soluble phenols, consisting essentially ofsubstituted polyhydric phenols of the class having hydroxyl groups inthe ortho and para positions and containing components of a sulfurdioxide extract of a cracked hydrocarbon distillate as substitutedgroups.

8. A product according to claim '7 in which the polyhydric phenols arederivatives of catechol."

9. A product according to claim 7 in which the polyhydric phenols arederivatives of pyrogallol.

CHARLES P. WILSON, JR.

